: Cleared PCM codes - now emissions test not ready

05-01-13, 08:10 PM
i did the onboard scan and scanned all codes and the cleared and reset all codes and they said that this is reason odb emmison couldn't get a reading or battery unplugged i told them i cleared all and reset.....is there certain codes that cant be deleted the will affect odm data? and also how do i get the emissions odb info info back in the computer asap thank you for info they said something like a drive cycle i have a 2003 deville also say if i just scan the pcm and delete a code will that delete odm info or if i delete a dss code? instead of scanning all and clearing all info

05-12-13, 04:56 PM
Any time you "clear all codes" the system will need either a dedicated GM Drive Cycle or a week or so of normal commuting during which no P emissions fault occurs in order to set the necessary "system ready" flags for the emissions test set. There's no need to ever "clear codes" - the system will automatically delete codes which do not again set after a specific number of successful start-run (not "drive") cycles.

If your car has a permanent or recurring P emissions code it will never pass emissions testing - until you diagnose and repair the problem that sets the code(s).

This is not the forum for normal PCM reset and car operation questions. Moved to Northstar Performance.